org.dspace.checker

Interface BitstreamDispatcher

All Known Implementing Classes:

HandleDispatcher, IteratorDispatcher, LimitedCountDispatcher, LimitedDurationDispatcher, SimpleDispatcher

public interface BitstreamDispatcher

BitstreamDispatchers are strategy objects that hand bitstream ids out to workers. Implementations must be threadsafe.

The rationale behind the use of the Sentinel pattern (rather than the more traditional iterator pattern or a cursor c.f. java.sql.ResultSet): -

1. To make it easy to make implementations thread safe - multithreaded invocation of the dispatchers is seen as a next step use case. In simple terms, this requires that a single method does all the work.
2. Shouldn't an exception as the sentinel, as reaching the end of a loop is not an exceptional condition.

Author:

Jim Downing, Grace Carpenter, Nathan Sarr

Field Summary

Fields

Modifier and Type	Field and Description
static int	SENTINEL This value should be returned by next() to indicate that there are no more values.

Method Summary

Methods

Modifier and Type	Method and Description
Bitstream	next() Returns the next id for checking, or a sentinel value if there are no more to check.

Field Detail

SENTINEL

static final int SENTINEL

This value should be returned by next() to indicate that there are no more values.

See Also:

Constant Field Values

Method Detail

next

Bitstream next()
               throws SQLException

Returns the next id for checking, or a sentinel value if there are no more to check.

Returns:

the next bitstream id, or BitstreamDispatcher.SENTINEL if there isn't another value

Throws:

SQLException - if database error